1. Field of Endeavor
The present invention relates to a pressing module for the press-forming and curing of impregnated conductor bars for large electrical machines, such as for example hydro generators, which includes an improved closing system for applying the pressing pressure, and further relates to a pressing apparatus equipped therewith.
2. Brief Description of the Related Art
It is known to wrap the conductor bars of large electrical machines with an insulating material, in particular a mica tape, and subsequently impregnate it with a curable resin. For the purpose of curing, the conductor bars treated in this way are placed in a pressing apparatus, in which they are pressed to the desired geometry. The pressing apparatus has a number of modules, formed of horizontal and vertical pressing units, which press the impregnated conductor bars into the required form.
In order to compensate for the volume shrinkage occurring during the curing, the pressing units must be continually readjusted, in order to avoid the occurrence of air pockets within the insulation, since air pockets would make the conductor bars unusable.
This object is achieved according to the prior art by wedges that are driven between the frame and the ram of the press, often manually by means of copper hammers. In the case of relatively large apparatuses, from time to time intermediate pieces are inserted between the wedge and the ram in order to compensate for major differences in length.
This work entails considerable personnel involvement and is therefore very costly and time-consuming.
In the case of this method, setting the varying pressing forces to be applied is very difficult to accomplish and is entirely dependent on the experience of the personnel concerned with carrying it out.
Furthermore, there is the latent risk that metal parts which splinter off during hammering may strike the insulation of the conductor bars and thereby cause damage to them. This can also lead to the finished conductor bars becoming unusable, or at least require them to undergo laborious reworking.